| Step | Reaction process | Mechanism |
|---|---|---|
| Adsorption | CO2（Solution）→ CO2* | Adsorption, forming M-O=C=O coordination |
| First-step electron transfer | CO2* + e⁻ → CO2⁻* | Formation of free radical anion intermediates (activation key) |
| Mass supply | CO2⁻* + H+ → *COOH | Formation of carboxylate intermediates, stability determines subsequent path |
| Second-step electron transfer | *COOH + e⁻ → *CO + H2O | Dehydration reduction, generating adsorbed CO |
| Desorption | *CO → CO | CO gas generation |
